The present invention relates to an internal combustion engine cylinder head structure of the overhead camshaft type and more particularly to an engine valve control mechanism.
U.S. Pat. No. 3,633,555 discloses a device for moving a cam relative to its driving shaft. This device is applicable to an internal combustion engine to vary the movement of the cams which control the intake and/or exhaust valves of the engine. This known device comprises a drive member rotatable with a driving shaft, and an intermediate member mounted in an external bearing which is eccentric with respect to the shaft. The shaft extends through an opening in the intermediate member dimensioned to allow limited movement of the bearing to vary the eccentricity. A cam is coaxial with the shaft and rotatable relative thereto. The device includes a first coupling between the drive member and the intermediate member at a first position spaced from the shaft axis, and a second coupling between the intermediate member and the cam at a second position angularly spaced from the first position with respect to the shaft axis. The two couplings are so spaced from the shaft axis that they are at varying distances from the axis of the intermediate member during operation. Each of these couplings has a movable connection with the intermediate member permit the variation in its distance from the axis the intermediate member.
GB-A 2 263 529 discloses an engine valve control mechanism incorporating a device similar to that shown in U.S. Pat. No. 3,633,555.
An object of the present invention is to improve an engine valve control mechanism employing the same control concept such that stress which the cylinder valve is subjected to is reduced sufficiently over the whole range of engine operation from low to high engine speeds.